Potassium-rich diet tied to lower stroke risk

NEW YORK (Reuters Health) - People who get plenty of potassium-rich foods in their diet may be less likely to suffer a stroke, a new research review finds.

The review, of 11 studies following more than 247,000 adults, found that as potassium intake went up, participants' risk of suffering a stroke went down.

That does not prove that potassium, itself, deserves the credit. But the foods highest in the mineral -- including many fruits and vegetables -- are considered generally healthy choices.

So the findings support experts' advice that people eat more fruits and vegetables to help cut their risk of cardiovascular disease and other ills, the researchers report in the Journal of the American College of Cardiology.

Potassium is an important mineral that helps regulate the heartbeat, conduct nerve impulses and contract muscles. Most adults need about 4,700 milligrams of potassium per day.

Potassium is found in a variety of fruits and vegetables, with potatoes, tomatoes, bananas, plums and raisins among the richest sources. Other sources include beans, dairy, nuts and molasses.

In theory, a diet with enough potassium could trim a person's risk of heart disease and stroke because the mineral helps lower blood pressure. But studies so far have come to mixed conclusions as to whether people who get plenty of potassium really do have fewer strokes and heart problems.

For the new study, researchers led by Dr. Lanfranco D'Elia, of the University of Naples Medical School in Italy, combined the results of 11 international studies that followed 247,510 adults for up to 19 years.

In most of the studies, participants filled out diet questionnaires at the outset, and researchers kept track of who developed heart disease or suffered a stroke over the ensuing years. In a few studies, the researchers measured participants' potassium levels from urine samples.

Individually, the studies came to conflicting results. But with the results combined, D'Elia's team found that for every 1,640-milligram increase in people's daily potassium intake, the odds of suffering a stroke declined by 21 percent.

There was no strong link overall between potassium intake and heart disease risk, though a few individual studies did find that people with higher intakes had a lower risk.

The 21-percent reduction in stroke risk would translate into as many as 1.15 million fewer stroke deaths worldwide each year, D'Elia's team estimates.

But whether potassium is actually the reason for the lower stroke risk is not clear.

In most of the studies, researchers tried to account for other factors in stroke and heart disease risk -- like overall health, weight, exercise habits and dietary fat intake. But people who get a lot of potassium could still have lifestyle habits or other characteristics -- like more education or higher incomes -- that might explain the lower stroke risk.

Still, D'Elia and his colleagues write, boosting potassium intake -- especially by eating more fruits and vegetables -- is in line with existing recommendations for preventing or managing heart disease and stroke.

There are some people, however, who may need to be careful about potassium intake and should ask their doctors before consuming more of the mineral. They include people with kidney disease, which can reduce the body's ability to clear potassium, and those on certain blood pressure drugs.

Too much potassium in the blood can lead to a condition called hyperkalemia, which can cause dangerous heart-rhythm disturbances.